The present invention relates to a method of harvesting timber trees in a jungle, and more particularly relates to a method of snigging or retracting fallen timber trees in a jungle, and machine used in the method to snig the harvested timber trees to a cleared site in the jungle.
It is known in the art relating to methods of forest harvesting, and particularly the harvesting of timber trees in tropical jungles, that the jungle ground is cleared of vegetation to allow the passage of lorries and cranes. The trees selected for harvesting are cut at their base, and allowed to fall generally in a predetermined direction. The fall of the trees damages all growth, including smaller trees and young saplings on the ground. The branches of the fallen tree are then cut off, and the timber trunk is snigged, or skidded, to a cleared area of the jungle for further cutting or loading into transport vehicles. The snigging or pulling of the trees along the ground further damages the vegetation on the ground. To enable lorries and cranes to reach the fallen tree, all vegetation on the path of travel for the lorries and cranes is removed. This causes further destruction of the vegetation or jungle cover. It is not uncommon, therefore, to find entire blocks of jungle laid barren in the harvesting and transporting of timber trees in tropical jungles. The known methods of transferring timber trees in tropical jungles typically result in the destruction of more than 60% of the jungle cover, a level of destruction that is totally undesirable.
Because of the destruction of young trees, saplings, and vegetation, the jungle cannot regenerate itself within a reasonable time. Under present practice, it takes more than 100 years before the re-harvesting of new timber trees can be considered in many tropical jungle areas. U.S. Pat. No. 4,114,666 to L. O. Bruum discloses a method of forest harvesting, and a machine for performing said method. The method and machine disclosed, though useful for harvesting timber trees in temperate or cultured forests, are not suitable for harvesting larger sized and branched tropical timber trees.
Another method of harvesting timber trees in tropical countries involves the use of helicopters. Helicopters are used to cut the crown of the tree, and to lift the cut tree to a logging yard. Although this method reduces damage to jungle cover to below 10%, it is not yet cost-effective or practical to continue use in harvesting an entire jungle area because the profit margins are greatly reduced, making the method economically unattractive.
Thus, there is a need for harvesters of tropical timber in tropical jungles to comply with the criteria laid down by the Forest Stewardship Council""s Principles and Criteria (PandC). More particularly, there is a need for an effective method of harvesting tropical timber trees, and to manage the manner in which the vehicles are used in snigging the cut timber trees within the logging area such that there is minimum destruction of the uncut timber trees and the undergrowth.
The present invention discloses a method of harvesting standing trees in a jungle that includes bringing a crawler crane with a boom to a block of jungle, securing the tree to be harvested to a sling in the boom, cutting the base of the tree, removing the cut tree using the boom, laying the cut tree on the ground, and cutting off the crown of the cut tree.
In another aspect of the invention, the method of harvesting standing trees in a jungle includes bringing a crawler crane with a boom to a block of jungle, securing the crown of a tree to be harvested to a sling in the boom, raising an operator to the crown portion of the tree, cutting the crown portion of the tree, removing the operator from the tree, removing the crown of the tree, and cutting the crownless tree at the base of the tree.
The crawler crane is preferably a hydraulic crawler crane. To enable the crawler crane to travel in the jungle, a main road is constructed across a predetermined area of the jungle, a spur road is constructed leading from the main road to a log landing area for a given sub-block of the jungle, and a plurality of snig tracks which extend radially from the log landing area are constructed in each sub-block of the jungle. In yet another aspect, a main road is constructed across a predetermined area of the jungle, and a plurality of spaced and parallel snig tracks are constructed extending from the main road, the distance between adjacent snig tracks being substantially equivalent to two to three times the length of the boom of the crane.
To attach the sling of the boom to the crown of the tree, and to cut the crown portion of a standing tree to be harvested, an operator is lifted to the crown portion of the tree in a steel cabin secured to the boom of the crane. The operator""s cabin of the crawler crane is fortified by means of a metal cage. The sides of the crane boom are enveloped by metal plate sidings to avoid or reduce the likelihood of entangling foliage within the lattice of the boom where the crane is used. The boom of the crawler crane is constructed to swing 360xc2x0 in a horizontal circle about the crawler, and to be raised up to 90xc2x0 in the vertical axis.
Typically the area of the jungle to be harvested when the crawler crane is positioned in the jungle is a circular area covered by the length of the boom of the crane, usually 60 meters. However this circular area of the trees to be harvested can be extended by the use of connector slings. Typically the circular area can be extended by an additional radial length of 16 meters.
Alternatively, and in another method of harvesting cut trees in a jungle, a crawler with a boom structure is brought to a predetermined block of the jungle, the harvested timber is secured to a winching cable on the boom structure, the crawler is stabilized, and the harvested timber is secured toward the crawler so that the harvested timber is moved in an inclined angle in relation to the ground. The winching cable is brought to the timber by securing it to an auxiliary winch cable of an auxiliary winch on the crawler, and retracting the auxiliary winch cable around an obstacle. The height of the boom structure is substantially more than 5 meters above ground so that the harvested timber is snigged in an inclined angle in relation to the ground to reduce obstruction and damages.
Another method of harvesting cut trees in a jungle includes constructing a main road across a predetermined area of jungle. A plurality of skid trails are then constructed leading from the main road, where the distance between adjacent skid trails is in the range of 200 to 300 meters.
A forest harvesting machine for practicing the above-described methods comprises a crawler with a boom structure, a winch assembly, and a foldable arm structure with grasping claws pivotally mounted along the boom structure. The foldable arm structure is used to stabilize the crawler during the snigging of harvested timber, and is operated by a hydraulic system. The crawler is stabilized on the ground by the foldable arm structure. A timber may be held on the ground by the grasping claws of the foldable arm structure for stabilizing the crawler. The crawler further includes an auxiliary winch assembly.
In another embodiment, the crawler has a boom structure mounted pivotally to a backhoe arm. A claw is secured to one end of the boom structure, and a roller guide assembly is secured to the other end of the boom structure. The crawler further includes an auxiliary winch assembly.
Further advantages and characteristics of the invention are given below in the description of the method of jungle harvesting of timber trees in a tropical jungle. Also described are the layout pattern of tracks, and an apparatus used in relation thereto, with reference to the accompanying drawings.